We use the following survey parameters.
The SPT surveys an area of 1500 \(\rm deg^{2}\) with a 6-\(\sigma \)  sensitivity of 15 mJy at 95 and 150 \(\rm GHz\) in one-week stacks [1]}.
The ACT surveys 18,000 \(\rm deg^{2}\) (40% of the sky) in a raster scan mode, scanning back and forth at constant elevation and allowing sources to pass through the field-of-view.
The cadence has been roughly one week since 2016.
The 1\(\sigma \)  sensitivity in a single sweep is 30–50 mJy at 90 \(\rm GHz\), but for a source that is steady across the time it takes to traverse the focal plane (approximately 10 minutes),
this is reduced to 10–20 mJy.
Here we take an RMS sensitivity of 15 mJy.
CMB-S4 [2]}, a next-generation cosmic microwave background (CMB) experiment, will conduct two surveys relevant for the discovery of transients like AT2018cow:
an all-sky wide-area survey (50% of the sky) and an ultra-deep survey in a smaller region (3%).
The CMB-S4 6-\(\sigma \)  sensitivity for one-week stacks is 18 mJy in the wide survey and 5 mJy in the deep survey [2]}.
